HW connections to STM32?

Hello all and Good morning…
I am trying to connect an STM32L476 to a Notecard for an application. I am using the Notecard-F Altium design and Swan Feather pdf schematics on github along with what I can find for information on the blues.io site. I have some questions I am hoping will clarify things:

  1. what is the difference between the Aux- uart and uart pinned out from the Notecard-F design? I am connecting my STM32 to the Aux-uart to send JSON commands but am not sure that is the correct connection?? (If using the Aux -uart do I need to enable it with a ‘1’ ?)

  2. From the design and website I cannot makeout the purpose of AUX1, AUX2, ATTN?

  3. Beginning to get the impression that AUX is for Firmware Updates and RX / TX is to be used for sending JSON data back and forth??


If i understand correctly from my research, aux pins are just gpio that you can trigger to do whatever. The ATTN pin is a pin that you can remotely wake up your MCU (if its sleeping etc) via some condition from the notecard.